This invention relates to a device actuator structure in a microfabricated electromechanical device.
Ink jet printers form an image by selectively depositing ink onto a receiving media. In a conventional ink jet printer system, the ink is stored in an ink storage unit, such as an ink reservoir or cartridge, and directed from the storage unit into a printhead, such as the printhead 100 shown in FIG. 1. In the printhead 100, ink flows into an ink pumping chamber 120 and to a nozzle 130, where the ink is ejected. Typically, the printhead includes an actuator that forces ink out of the printhead 100 through the nozzle 130. Two common types of actuators include resistive heating actuators and piezoelectric actuators. In a piezoelectric actuator 150, a layer of piezoelectric material 165 can be formed adjacent to the ink pumping chamber 120. Applying a voltage across the piezoelectric material 165 causes the piezoelectric material to bend or deform. The deformation of the piezoelectric material 165 causes a pressure wave to propagate through the ink pumping chamber 120, pushing ink out of the nozzle 130 and onto the receiving media. Typically, electrodes 160, 170 are formed on either side of the piezoelectric layer 165 to enable voltage to be applied across the layer 165.
In so-called “drop on demand” printers, multiple individual flow paths each with an associated pumping chamber 120 and nozzle 130, can be formed in a single printhead 100 and each nozzle 130 can be individually activated. Thus, a particular nozzle fires only when a droplet of ink from that nozzle is desired. To activate a particular actuator on the printhead, an electrical signal can be individually communicated to that actuator.